An animation within an animation
I'd see two potential ways:


use an intermediate empty, plus parenting and constraints, which is a little finnicky to set up, or
use a group instance


Method 1



The idea is to use an empty, and first parent the circle (your already working path) to it. Then add a child of constraint to the main bone of your armature, and make sure to click set inverse right after that. Now both the armature and the curve follow the empty. move the empty to the scene origin, and the second curve as well. Use the follow path constraint on the empty to target the second curve and set the parameters as you like.







Method 2



Select every object which the pendulum is made of - that includes the armature object and the curve - and hit Ctrl + G to create a group around it. Name it appropriately (I chose Pendulum). Make sure to also use the Offset from Cursor function like in the GIF. Basically, this allows you to define the Origin Point of the instance relative to the current cursor position. Then, use Shift + A and add a group instance of Pendulum to the scene. Use the follow path constraint on this new instance.



Personally, I find method number 2 far less convoluted and error-prone, but what fits your situation best is up to you.